(1) In ~/.ssh/authorized_keys, prefix the ssh key with command="/home/bob/zzzzz.sh"
(2) In the script /home/bob/zzzzz.sh , filter the connection according to the environment variable SSH_ORIGINAL_COMMAND as shown on the above page.

The problem is that the ssh connection does not provide the environment variable SSH_ORIGINAL_COMMAND when the ssh user is chrooted with Jailkit.

I suspect that jailkit is filtering the environment variable. This is probably not a ssh server issue since the environment variable is there when the account is not chrooted.

I would appreciate some advices before I contact the site administrator (ideally with the solution)